linux-kernel - Re: [PATCH] i2c: cp2615: replace deprecated strncpy with strscpy

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Message-ID: <202309200822.67A5B4B61@keescook>
Date:   Wed, 20 Sep 2023 08:23:16 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Justin Stitt <justinstitt@...gle.com>
Cc:     Bence Csókás <bence98@....bme.hu>,
        Andi Shyti <andi.shyti@...nel.org>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] i2c: cp2615: replace deprecated strncpy with strscpy

On Wed, Sep 20, 2023 at 08:08:52AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> 
> We should prefer more robust and less ambiguous string interfaces.
> 
> We expect name to be NUL-terminated based on its numerous uses with
> functions that expect NUL-terminated strings.
> 
> For example in i2c-core-base.c +1533:
> | dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
> 
> NUL-padding is not required as `adap` is already zero-alloacted with:
> | adap = devm_kzalloc(&usbif->dev, sizeof(struct i2c_adapter), GFP_KERNEL);
> 
> With the above in mind, a suitable replacement is `strscpy` [2] due to
> the fact that it guarantees NUL-termination on the destination buffer
> without unnecessarily NUL-padding.
> 
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: linux-hardening@...r.kernel.org
> Signed-off-by: Justin Stitt <justinstitt@...gle.com>

Thanks for the clear commit log! Looks good to me.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook